1. Field of the Invention
The present invention relates to a continuous separator plate for use with a disk drive. More particularly, the present invention relates to a continuous separator plate for use with a disk drive that has improved shock resistance allowing for a smaller gap between the continuous separator plate and a rotating disk of the disk drive, which further provides for improved air dampening characteristics to aid in suppressing rotating disk and head vibration.
2. Description of the Prior Art and Related Information
A huge market exists for hard disk drives for mass-market host computer systems such as servers, desktop computers, and laptop computers. To be competitive in this market, a hard disk drive should be relatively inexpensive, and should accordingly embody a design that is adapted for low-cost mass production. Further, there exists substantial competitive pressure to continually develop hard disk drives that have increasingly higher storage capacity, that provide for faster access to data, and at the same time conform to decreasingly smaller exterior sizes and shapes often referred to as “form factors.” Specific methods that are presently being employed to decrease access times to data are to increase the density of tracks on each disk and to increase the rotational speed of the disk(s) of the disk drive.
Satisfying these competing constraints of low-cost, small size, high capacity, and rapid access to data requires innovation in each of numerous components and methods of assembly including methods of assembly of various components into certain subassemblies. Typically, the main assemblies of a hard disk drive are a head disk assembly and a printed circuit board assembly.
The head disk assembly includes an enclosure including a base and a cover, at least one disk having at least one recording surface, a spindle motor for causing each disk to rotate, and an actuator arrangement. The printed circuit board assembly includes-circuitry for processing signals and controlling operations. Actuator arrangements can be characterized as either linear or rotary; substantially every contemporary cost-competitive small form factor drive employs a rotary actuator arrangement.
The rotary actuator arrangement is a collection of elements of the head disk assembly; the collection typically includes certain prefabricated subassemblies and certain components that are incorporated into the head disk assembly. The prefabricated assemblies include a pivot bearing cartridge and, in some cases, a prefabricated head stack assembly which may include the pivot bearing cartridge. Other components of the rotary actuator arrangement are permanent magnets and an arrangement for supporting the magnets to produce a magnetic field for a voice coil motor. The prefabricated head stack assembly includes a coil forming another part of the voice coil motor. The prefabricated head stack assembly also includes an actuator body having a bore through it, and a plurality of actuator arms projecting parallel to each other and perpendicular to the axis of the bore. The prefabricated head stack assembly also includes head gimbal assemblies that are supported by the actuator arms. Each head gimbal assembly includes a load beam and a head supported by the load beam. The head is positioned over a track on a recording surface of the disk to write or read data to or from the track.
As previously discussed, a typical head gimbal assembly includes a load beam, and further, a gimbal is attached to an end of the load beam, and the head attached to the gimbal. The load beam has a spring function that provides a “gram load” biasing force and a hinge function that permits the head to follow the surface contour of the spinning disk. The load beam has an actuator end that connects to the actuator arm and a gimbal end that connects to the gimbal that carries the head and transmits the gram load biasing force to the head to “load” the head against the disk. A rapidly spinning disk develops a laminar airflow above its surface that lifts the head away from the disk in opposition to the gram load biasing force. The head is said to be “flying” over the disk when in this state.
Because of the competitive pressure to continually develop hard disk drives that provide for faster access to data, techniques and solutions to problems are continuously being developed to increase the reliability of accessing data and to decrease the access time to data. One source of problems related to the performance of disk drives are track misregistration errors (TMRs). Track misregistration errors detrimentally affect the performance of the disk drive and increase the access time to data.
As previously discussed, one particular method that is presently being employed to decrease access times to data is to increase the rotational speed of the disk(s) of the disk drive. Although increasing the rotational speed of the disks of the disk drive advantageously decreases access time to data, or latency times (i.e. time spent waiting for a selected data block to reach the head as a particular disk rotates), higher rotational speeds tend to induce a greater degree of turbulence in the airflow established by the rotating disks. It is desirable to have laminar or uniform airflow about the disks, HSA, and heads, as opposed to turbulent airflow. Turbulent airflow is characterized by random fluctuations in the speed and direction of the airflow. Such turbulence can cause unwanted vibration of the disks and the heads, leading to undesirable track misregistration errors.
One way of counteracting this turbulent airflow, which has been used in the past, includes utilizing a separator plate mounted above and/or below a rotating disk to form a channel therebetween to provide air dampening and to thereby reduce air turbulence. These conventional separator plates typically include an open portion to accommodate the head stack assembly (HSA). For example, as shown in FIG. 1A, a separator plate 10 having an open portion 11 is illustrated. The separator plate 10 has a first unsupported tip 12 and a second unsupported tip 14 at opposite ends of the open portion 11. Unfortunately, the deflection of the first unsupported tip 12 and the second unsupported tip 14 of the separator plate 10 are relatively large in response to shock events, and therefore, a relatively large gap is required between the separator plate 10 and the rotating disk.
For example, FIG. 1B is a graph 16 illustrating the deflection (in millimeters (mm)) of the first unsupported tip 12 and the second unsupported tip 14 of the separator plate 10 in response to a −300 G; two millisecond (ms) shock event, for a period of 4 ms. As can be seen in FIG. 1B, the second unsupported tip 14 varies between an approximate maximum +1.4 mm deflection and an approximate −1.3 mm deflection (plot line 20) and the first unsupported tip 12 varies between an approximate maximum +0.85 mm deflection and an approximate −0.6 mm deflection (plot line 22). Unfortunately, because of these relatively large deflections in response to a shock event, the gap between the separator plate and the rotating disk needs to be designed to be relatively large to accommodate these relatively large deflections.